Study Guide DNA Unit

Question 1

Chromosome

Answer 1

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Question 2

Protein

Answer 2

made up of one or more long, folded chains of amino acids (each called a polypeptide), whose sequences are determined by the DNA sequence of the protein-encoding gene.

Question 3

Amino Acid

Answer 3

the fundamental molecule that serves as the building block for proteins

Question 4

DNA

Answer 4

Stands for deoxyribonucleic acid and contains genetic information, found in chromosomes located in nucleus of cells, composed of nucleotides (a single unit), contains sugar molecule (deoxyribose), phosphate group, nitrogen containing base (A,T,G,C). Double helix- two coiled DNA strands

Question 5

Mitochondrial DNA

Answer 5

mtDNA. Found in the cytoplasm, is inherited only from mother. Each cell contains hundreds to thousands of mitochondria, can be found in skeletal remains. Analysis of mtDNA is more: rigorous, time consuming, costly than nucleic testing of DNA

Question 6

Nucleotide

Answer 6

the basic building block of nucleic acids (RNA and DNA). A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T)

Question 7

Complementary base pairing

Answer 7

adenine will always pair with its complement thymine and cytosine will always pair with its complement guanine

Question 8

Semi conservative replication

Answer 8

Each DNA molecule resulting from replication has one original strand and one new strand

Question 9

Mutation

Answer 9

Any change in the DNA sequence of a cell AKA an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect

Question 10

VNTRs

Answer 10

Variable Numbers of Tandem Repeats- a type of repeating DNA sequence, the number of repeats varies from person to person, 9 to 80 bases in length

polymerase chain reaction (PCR) can be used to amplify the DNA that contains the VNTRs

Question 11

Short Tandem Repeat

Answer 11

STR’s which are 2-5 bases in length. Shorter lengths make STR’s easier to use than VNTR’s

restriction enzymes are unnecessary; PCR allows the
amplication of the strands with STR sequences

Question 12

DNA profiling/fingerprinting

Answer 12

used with a high degree of accuracy, biological evidence is examined for the presence of inherited traits. Some forensics laboratory techniques were originally developed for other purposes

Question 13

PCR

Answer 13

(Polymerase chain reaction) allows the amplification of the strands with STR sequences. a laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail

Question 14

Gel Electrophoresis

Answer 14

Bands of DNA are separated by size using electric current, DNA is mixed special enzymes, enzymes cut apart the DNA in specific places forming different sized fragments, DNA is separated within an agarose gel, an electric current is passed through the gel separating the fragments by size

Question 15

Hydrogen bonds

Answer 15

bonds between bases hold the two strands together, G-C has 3, A-T has 2, can be broken easily, two strands can separate to be copied

Question 16

CODIS

Answer 16

an acronym for Combined DNA Index System, which is a computer software program that operates local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons

Question 17

Denaturation

Answer 17

(Healing) - heat briefly to separate DNA strands. Due to abrupt changes in environmental conditions like temperature, pH etc., the DNA double helix unwinds and the hydrogen bonds between the base pairs are broken. favorable to DNA hybridization

Question 18

Annealing

Answer 18

(Cooling)- cool to allow primers to bond with ends of DNA.

Question 19

Extension

Answer 19

DNA polymerase adds nucleotides to the end of each primer

Question 20

Primer

Answer 20

a short nucleic acid sequence that provides a starting point for DNA synthesis

Question 21

DNA polymerase

Answer 21

enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA

Question 22

Reasons to use DNA fingerprinting

Answer 22

identifying potential suspects, exonerating individuals (finding them not guilty/set free), identifying crime scenes and victims (burned bodies, decomposed bodies, etc), establishing paternity and proving family relations, matching organ donors, identifications of john doe or jane doe, studying evolution and ancestry (through nuclear and mitochondrial DNAs), studying inherited disorders

Question 23

Steps of DNA replication

Answer 23

DNA molecule separates into two strands.

Then produces two complementary strands.

Each strand of the double helix of DNA serves as a template, or model, for the new strand

Question 24

Steps of DNA fingerprinting

Answer 24

Extraction, Amplification, Gel Electrophoresis and Probes

Question 25

Steps of DNA extraction

Answer 25

1. Cells are isolated from biological evidence such as blood, saliva, urine, semen and hair
2. The cells are broken to release the DNA from proteins and other cell components
3. The DNA can be extracted from the cell nucleus

Question 26

Steps of PCR amplification

Answer 26

1. Denaturation (heating)
2. Annealing (cooling)
3. Extension

Question 27

Steps of gel electrophoresis

Answer 27

Bands of DNA are separated by size using electric current

DNA is mixed with special enzymes

Enzymes cut apart the DNA in specific places forming different sized fragments

DNA is separated within an agarose gel

An electric current is passed through the gel separating the fragments by size

NOTE: Shorter=faster, Longer=slower

Question 28

How do restriction enzymes work?

Answer 28

What are restriction enzymes and how do they work?
Restriction enzymes are DNA-cutting enzymes. Each enzyme recognizes one or a few target sequences and cuts DNA at or near those sequences

Question 29

What did James Watson, Francis Crick and Rosalind Franklin do?

Answer 29

they discovered the configuration of the DNA molecule

Question 30

What did Ray White do?

Answer 30

he described the first polymorphic RFLP marker

Question 31

What did Alec Jeffreys do?

Answer 31

he isolated DNA markers and called them DNA fingerprints

Question 32

What did Kary Mullis do?

Answer 32

he developed PCR testing